The purpose of this research is to study natural resistance to gonorrhea in women. Since the gonococcus can be phagocytosed by polymorphonuclear leukocytes and killed by the joint action of complement and antibody of normal women, these 2 immune mechanisms are considered to be important factors in local and systemic resistance to gonorrhea. In order to determine the role of the complement-antibody and phagocytic systems in natural resistance to gonorrhea, their activity against gonococci will be studied during different phases of the menstrual cycle and pregnancy, under chemical conditions met in the genital tract, and in the presence of its normal flora. Such a study might indicate if natural resistance to gonorrhea in women is subject to the influence of endocrine changes during the menstrual cycle and to the chemical and microbial conditions that are unique to the female genital tract.